Single-powder photographic developers



Patented Sept. 11, 1945 SINGLE-POWDER rno'rooasrmc nsvstornas- Frederic R. Bean, Rochester, N. Y., assignor to Eastman Kodak Company, Rochester, N. Y., a corporation of New Jersey No Drawing. Application April 22, 1943,

. Serial No. 484,061

' Claims. (01.95-88) This invention relates to single-powder photographic develdpers wherein all ingredients of the developer are intimately mixed together in dry powder form.

Such mixtures are in themselves known. Their preparation has heretofore centered around stabilizing the organic developer either by 00- precipitating it with stabilizers or by preparing stable derivatives of it, which then break down into their active components when put into solution. While these preparations proved moderately successful, it has until now nevertheless not been possible to prepare single-powder photographic-developers containing in intimate admixture, in dry powder form, both an organic developer and an alkaline constituent, such as an alkali carbonate, as under these conditions they would undergo decomposition reactions resulting in the destruction of the activity of the developer. Thus it was not possible to prepare such mixtures for storage or packaging; for such purposes the alkali ingredient and the organic developer always had to be carefully kept separate in different compartments or containers.

It is therefore an object of this invention to overcome the aforesaid dimcultiesby preparing single-powder photographic developers which will keep and remain stable. I I

A further object of this invention is to prepare stable single-powder photographic developer mixtures containing an organic developing agent, whereby the term developing agent" is to be understood as comprising either one or several separate organic developer compounds, such as shown by examples given herein below.

It is still a further object of this invention to prepare single-powder photographic developers containing both an organic developing agent and a preferred type of alkaline or basic compound in the presence of, and intimate admixture with, the other ingredients, notably, a stabilizing component, which latter is to be understood as comprising either one'or several separate stabilizing substances, as illustrated in examples given hereinafter. Other objects will appear from the following description of the invention.

/ In accordance with my invention, these and sultant aqueous developer solution. The alkalinity of the basic substances used is within the range of the alkali borates, carbonates, and phosphates, and stabilization of them may be achieved with one or more of these stabilizing agents. The degree of stability attained has been found to vary directly with thequantity and type of stabilizer or stabilizer admixture and the type of basic substance employed with a given concen-' tration of developing agent in such single-powder developer mixture.

In the following examples I have given several of the preferred embodiments of my invention, but it is to be understood that they are ,set forth for the purpose of illustration only and not in limitation thereof.

The stabilizing substances forming the object of the invention comprise both organic and inorganic solid compounds which, in order to be suitable as stabilizers, should preferably be relatively colorless, odorless, and stable; they should have no deleterious action photographically; they should be of an acidic nature and should, in addition, be readily adsorbable on the surfaces of the ingredients of the single-powder developer, especially on the surfaces of the alkaline ingredients, thereby tending to exert an antidiscolorant action. One may thus expect that the degree to which the foregoing characteristics are found combined in one substance or in a combination of them, to that same extent will that substance or combinationof substances present stabilizing properties. Examples of such substances are the alkali metabisuliltes, phthalic anhydride, maleic anhydride, benzoic anhydride, salicylic acid, 0-

benzoic sulilmide, and phthalimide. The presence of alkali metabisulfltes in developer compositions is not new, where they have been employed thus far as preservatives, 1. etc lessen the rate of oxidation of the organic developing agent present (in the developer solution). But accordother objects are accomplished by selecting an inorganic and/or organic compound from a group of acidic substances possessing stabilizing prop- 1 erties, such as described hereinafter, and incorporating the selected compound or compounds in the proposed single-powder photographic developer mixture together with the other ingredients, among these being the organic developing ing to the present invention, it has been found that the alkali metabisulfltes, particularly the potassium metabisulflte, will also'act as a' stabilizer in the singlel powder developer mixture, 1. e. it will preventor inhibit reaction between the alkali component and the organic developing agent jointly present in admixture in. the dry. singl'e powder developer mixture, particularly if the alkali be a stable alkali carbonate monohydrate, such as according to this invention.

Thus, a preferred embodiment of the invention involves the use, in the said single-powder photoagent and an alkaline component, the characteristics of the latter being that it be stable in itself graphic developer mixture, of either the stable 1 hydrate of" an alkalicarbonateor also a desiccated alkali carbonate. Generally, the stable under ordinary conditions of temperature, pressure and atmospherichumidity, that it be soluble and photographically compatible lathe-re alkali carbonate hydrate, particularly the a all carbonate.{anonohydrate, is to 'be preferred, as hown it to be much more] have" stable in the presence of an organic developing agent than a comparable quantity of the corresponding desiccatedalkali carbonate. In most instances the sodium carbonate monohydrate single-powder developers are more easily and completely stabilized than those developer :com-

positions containing an anhydrous alkali carbonate.

.Ilhe invention is broadly applicable to stabilization with an acidic substance of an organic developing agent, such as elon, hydroquinone, paraphenylene diamine sulfate, paraminophenol sulfate, glycin, metoL-and others, in the presence of a soluble and stable basic substance of medium-to-mild alkalinity and photographic compatibility. Thus, phthalic anhydride has outstanding stabilizing properties in the presence of either sodium carbonate monohydrate, desiccated sodium carbonate, or borax. Other sub-.

stances, such as maleic anhydride and salicylic acid are only mildly eflective with sodium car- 'Alkali metabisuliite.

bonate monohydrate. benzoic anhydride, orthobenzoic sulflmide, and

-phthalimide, either. singly or in admixture, are

particularly eflective as stabilizers with alkali carbonate monohydrates.

Potassium metabisuliite in conjunction with one of the organic stabilizers, preferably phthalic anhydride, has proved to be a very good stabilizer admixture, especially in an alkali carbonate monohydrate or in a desiccated alkali carbonate when used in the requisite monohydrate; and a stabilizer, such as an alkali metabisulfite, preferably the potassium metabisulflte and/or phthalic anhydride, and may contain the other ingredients normally present in a developer, such as sodium sulflte and potassium bromide, the normal and known function of the alkali sulfite being that of preservative, lessening the oxidation in solution of the organic developing agent, while the known function of potassium bromide is that of a restrainer, particularly in-.

hibiting fog" formation in the development of the silver image. These known components and their known functions in a photographic developer are not to be considered as forming part of this inventio nor is their mention herein to be construed as delimiting thereto the scope of the proposed single-powder developer mix- In compounding the developer mixture, one mayproceed by first mixing the stabilizer and the basic component, adding and admixing thereupon the developing agent, which is followed by the other ingredients. However, if so preferred, all ingredients may also be mixed simultaneously.

- In another method of preparing the mixture, the

stabilizer is vaporized and in the vapor state is diffused into the powdered alkali, such as, for

example, by the sublimation of phthalic anhypowder photographic developer mixture. f

Example 1 Grams Elon 0.62

Hydroquinnnn 240 5 Sodium carbonate monohydrate 21.60

Potassium metabisuiilte ..-11.1 Potassium br e 0.38 Sodium sulflte, anhydrous 0.0 m The quantity of developer representedby the foregoing formula can be directly dissolved in water tomake 400 c. c. of developer solution ready for immediate use; it also can be made up into a stock solution of 200 c. c., which on use is to be diluted 1:1. A very large 'quantity or proportion of potassium metabisulilte is used in this example. Single-powder developers made up according to this example remained unchanged (no discoloration) after storing for more than 18 months as a dry powder.

Example 2 Grams Elon 4 6.2 Hydroqnlnnnfl 24 25 Sodium carbonate monohydrate 165 Potassium metabisulflte 1 Potassium bromide 3.8 Sodium sulflte, anhydrous 78 The quantity of developer. given by Example 1 is suilicient to prepare a developer stock solution of 2 liters, or 4 liters ready for immediate use.

Example 3 a Grams 36 Elon 0.62

Hydroqninnna 5 2,4 Sodium carbonate monohydrate 16.0 Phthalic anhydride 1 0.5 Potassium bromides 0.38 40 Sodium sulflte, anhydrous 9.0

Esample 4 Grams Elon 0.62 Hydroquinnne 2.4 Sodium carbonate, desiccated 13.5 Phthalic anhydride 0.5 Potassium br de 0,33 Sodium sulilte, anhydrous 9.0

of phthalic anliydride were 0.2 gram and 0.1

I Example 5 Grams Elon 49.6 Hydroquinnnn 19,2 -Sodium carbonate monohydrate 1320.0 Potassium metabisuliite. 88.0 Phthalic anhydride 40.0 Potassium bromide-.. 30.4 Sodium su'lflte, anhydrous 624.0

Example 6 v Grams Elon 49.6 Hydroqui 19.2 Sodium carbonate, desiccated -1- 1160.0 Potassium metabisulflte sac 'Phthalic anhydride 20.0 Potassium bromide 30.4 Sodium sulflte, anhydrous 624.0

Some of these single-powder mixtures containing small amounts of stabilizers remain colorless for 2 to 6 months-and with a very large quantity The quantity per volume of developer solution that can be prepared by the formulas of the foregoing examples depends upon the concentration of the developing agent in the developer mixture and upon its concentration as desired in the developer solution and the purposes for which it is to be used. Known developer formulas may serve as a guide in this matter. It can, however, be said that 500 grams of such single-powder photographic developer mixture will be suflicient to prepare approximately 3.5 liters of developer solution used for general developing purposes.

Under some circumstances it may be advantageous to add a wetting agent to the singlepowder developer, in order to increase the speed of solution in water.

But theinvention is not to be limited to these examples, as numerous other mixtures and equivalents can be made up, varying both quantitatively and qualitatively, while still retaining the desirable characteristics of a single-powder developer mixture, such as hereinbefore described.

It was also found that the potassium form of the metabisulflte is superior to the sodium metabisulnte as a stabilizing agent.

In special cases it is also possible to use sodi sesquicarbonate dihydrate in place or sodium car'- bonate monohydrate as an alkali in single-powder developers.

The developer powder may also contain an aldehyde-bisuliite, such as sodium formaldehyde bisulnte.

Single-powder photographic developer mixtures of the type described, by reason 01' the invention obviate the necessity of separately packaging first the developer portion containing the organic Example 7 Grams Hydroquinone 2.0 Sodium sulflte, anhydrous 75.0 Sodium carbonate, desiccated 50.0 Potassium bromide 3.0 Potassium metabisulflte 11.0 Phthalic anhydride 3.0

Example 8 Grams Hydroquinone 2.0 Sodium sulflte, anhydrous 75.0 Sodium carbonate monohydrate 58.5 Potassium bromide 3.0 Potassium metabisulfite 11.0 Phthalic anhydride 3.0

Erample 9 Grams Elon 8.0 Sodium sulflte, anhydrous 400.0 Hydroquinone 20.0 Borax 50.0 Phthalic anhydride 10.0

Example 10 Grams I Elon 0.62

Hydroquinone 2.4 Sodium sulfite, anhydrous 9.0 NaaPOr-mo 12.0 KBr 0.38 Phthalic anhydride 0.5

developing agent proper, and then the other portion containing the alkaline component; thus, this otherwise intricate packaging operation is much simplified, resulting in a considerable saving of time, labor, and packaging material. The packaging is expedited, and less costly containers can be used with this single-powder developer mixture. Furthermore, the developer mixture thus prepared and packaged will be ready for instant'use, requiring merely solution in a proportionate quantity of water.

What I claim is:

l. A single-powder photographic developer composition, substantially as described, containing an organic developing agent; a soluble, stable and photographically compatible basic ingredient selected from the group consisting of alkali borates, carbonates, sesquicarbonates, and phosphates; and phthalic anhydride.

2. A single-powder photographic developer composition, substantially as described, containing an organic developing agent; a, soluble, stable, and photographically compatible basic ingredient selected from the group consisting of alkali borates, carbonates, sesquicarbonates. and phosphates; and an alkali metabisulflte and phthalic anhydride.

3. A single-powder photographic developer composition, substantially as described, containing an organic developing agent; sodium carbonate monohydrate; potassium metabisulflte; and phthalic anhydride.

4. A single-powder photographic developer composition, substantially as described, prepared by admixing an organic developing agent; sodium carbonate monohydrate; and phthalic anhydride.

5. A single-powder photographic developer composition, substantially as described, containing in intimate admixture, in the dry state, an

organic developing agent, phthalic anhydride and trisodium phosphate monohydrate.

6. A singlepowderphotographic developer composition, substantially as described, contaming in intimate admixture, in the dry state, an organic developing agent, phthalic anhydride, and borax (sodium tetraborate).

7. A single-powder photographic developer composition, substantially as described, containing in intimate admixture, in the dry state, an organic developing agent, an acidic stabilizing component including phthalic anhydride, and borax (sodium tetraborate). I

8. A single-powder photographic developer composition, substantially as described, containing in intimate admixture, in the dry state, an organic developing agent, phthalic anhydride an an alkali carbonate monohydrate.

9. A single-powder photographic developer composition, substantially as described, containing in intimate admixture, in the dry state, an organic developing agent, phthalic anhydride and an alkali metabisulfite and an anhydrous alkali carbonate.

compounds. a

i I'REDERIC R. BEAN.- 

